the latest abc news/"washington post" poll shows 57% would vote for clinton in a 2016 presidential bid. >>> turning now to news overseas. all eyes are on two tense situations developing by the hour that could have serious implications for the united states. in syria, with the assad regime growing increasingly desperate, intelligence reports indicate that a chemical attack against his own people could be imminent. even russia, syria's most powerful ally, is alarmed. their foreign minister met yesterday with secretary clinton, discussing the possibility of a syria without assad in power. this morning, rebels have declared damascus's airport a military target, warning civilians and airlines not to approach it. >>> and in egypt, tanks and barbed wire barricades returned to the streets of cairo as deadly protests raged outside the presidential palace. egyptian president mohamed morsi is calling for a national dialogue but is resolute about his controversial constitution. nbc's ayman mohyeldin is joining us live from cairo monitoring the situation. let's start with egypt. how much more troub